text: Acetogenesis is a type of microbial metabolism that uses hydrogen () as an electron donor and carbon dioxide () as an electron acceptor to produce acetate, the same electron donors and acceptors used in methanogenesis (see above).  Bacteria that can autotrophically synthesize acetate are called homoacetogens.  Carbon dioxide reduction in all homoacetogens occurs by the acetyl-CoA pathway.  This pathway is also used for carbon fixation by autotrophic sulfate-reducing bacteria and hydrogenotrophic methanogens.  Often homoacetogens can also be fermentative, using the hydrogen and carbon dioxide produced as a result of fermentation to produce acetate, which is secreted as an end product.